Noise pollution exacts a toll on all in the society. This toll can include adverse effects that run the gamut and can include hearing impairment, stress, impediments to understanding a normal conversation and insomnia.
The existence of noise pollution in certain environments is well documented. For example, highways in densely populated areas are chronic sources of unwanted noise. As a result, one solution that has achieved extensive acceptance in communities involves building a wall along the highways. This wall serves a plurality of purposes. First, stray animals are kept from wandering onto the highway. Second, a wall of sufficient height will abate the noise from the highway immediately adjacent the road i.e. by creating a noise "shadow" adjacent the wall.
To a certain extent, it is true that there is a "shadow" on the side of the wall opposite from the highway where a sound wall is effective. However, it has been observed that a "plume" of noise will still breach the wall and instead affect an adjoining area, perhaps several blocks away from the highway. Thus, while one area immediately adjacent the wall has been protected somewhat, in effect the problem will have been diverted to an area some distance away which heretofore had been immune from the objectionable noise due to the noise having been dissipated closer to the highway by the defacto sound "baffles" that are present. Examples of such sound baffles would include shrubbery, buildings and topological variations of the terrain.
The following patents reflect the state of the art of which applicant is aware and has been included herewith to discharge applicant's acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these patents teach singly, nor render obvious when considered in any conceivable combination, the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed.
______________________________________ PAT. NO. ISSUE DATE INVENTOR ______________________________________ 3,812,931 May 28, 1974 Hauskins, Jr. 4,069,768 January 24, 1978 Matsumoto, et al. 4,226,299 October 7, 1980 Hansen 4,436,179 March 13, 1984 Yamamoto, et al. 4,583,615 April 22, 1986 Amram 4,899,846 February 13, 1990 Furuta, et al. ______________________________________
Each of these patents can be characterized as providing a "passive" form of sound abatement in which a physical impediment such as a wall impedes the migration of sound waves that emanate from the highway. The sound waves contact the wall and the wall merely opposes the sound wave transmission. In effect, the wall is a passive barrier. As mentioned above, while there is a noise abated "shadow" cast on the other side of the wall, the noise reflected from or spilling over such a passive barrier is redirected to other areas.